Mapping Important Shark and Ray Areas (ISRAs) in the Central and South American Pacific: Existing knowledge and data needs

Abstract

Identifying critical habitats is key to the conservation and recovery of threatened species. A third of chondrichthyans (sharks, rays, and chimaeras) are threatened with extinction but robust biological and ecological information to delineate critical habitats for many species remains limited. Here, we investigated (1) research outputs and trends across the Central and South American Pacific region to determine whether sufficient information was available to identify critical habitats; (2) whether regional Important Shark and Ray Areas (ISRAs) were spatially representative; (3) what species and which ecological traits were most commonly used in the delineation of critical habitats; and (4) discuss how ISRAs can inform research priorities and area-based management in support of chondrichthyan conservation. Sixty-five ISRAs were identified for 97 of 190 chondrichthyan species occurring in the region (51%). Across key life-history processes, reproductive areas were most identified (n = 50). Of 821 published studies (2,160 entries), 31.48% (28% entries) primarily focused on fisheries and 48.51% included enough information to inform the ISRA process. Most (58.98%) of these studies originated from Mexico (n = 342, 744 entries) and Ecuador (n = 147, 276 entries). France and Honduras had the least regional research outputs relevant to apply the ISRA Criteria. Significant ecological data gaps were identified in oceanic (including areas beyond national jurisdiction), deepwater (>200 m), and along the southern part of the region (i.e., southern Chile). Deepwater species, chimaeras, and 21% of threatened species had knowledge gaps that did not allow the identification of ISRAs. If area-based management decisions in this region were based on ISRAs, and effectively implemented and enforced, diversity hotspots and at least 97 species could receive protection, including 79% of threatened species and 54% of those considered range-restricted. Increased monitoring and research efforts, with a corresponding increase in funding to fill existing gaps is key to support the identification of important habitats across this region.

Fig 1. Important Shark and Ray Areas (ISRA) identified in the Central and South American Pacific region.

(a) Three-letter codes inside the Exclusive Economic Zones (EEZ) represent the corresponding jurisdictions. CHL: Chile, COL: Colombia, CRI: Costa Rica, ECU: Ecuador, FRA: France, GTM: Guatemala, HND: Honduras, MEX: Mexico, NIC: Nicaragua, PAN: Panama, PER: Peru, SLV: El Salvador. (b) Numbers represent each subregion within the Central and South American Pacific region. 1: Gulf of California, 2: Offshore Eastern Pacific, 3: Pacific Central American Coastal, 4: Southeast Pacific, 5: Humboldt Current, 6: South American Southern Ocean. EEZ boundaries were reprinted from Flanders Marine Institute (2023) Maritime Boundaries Geodatabase: Maritime Boundaries and Exclusive Economic Zones (200NM), version 12. Available online at https://www.marineregions.org/. https://doi.org/10.14284/632 under a CC BY 4.0 international license.

Fig 2. The six subregions of the Central and South American Pacific with information on the number of ISRA (in parenthesis) delineated and the ISRA Criteria applied in each.

Two movement areas spanned multiple subregions and were not included in this figure. ISRA Criteria are: A: Vulnerability; B: Range Restricted; C1: Reproductive Areas; C2: Feeding Areas; C3: Resting Areas; C4: Movement Areas; C5: Undefined Aggregations; D1: Distinctiveness; D2: Diversity.

Fig 3. IUCN Red List of Threatened Species extinction risk status for the 75 Qualifying Species in Important Shark and Ray Areas in the Central and South American Pacific.

CR: Critically Endangered; EN: Endangered; VU: Vulnerable, NT: Near Threatened; LC: Least Concern; DD: Data Deficient.

Fig 4. Shark, ray, and chimaera families included as Qualifying Species within an Important Shark and Ray Area (ISRAs) in the Central and South American Pacific region.

Numbers in parentheses indicate the number of species for each family occurring in the Central and South American Pacific.

Fig 5. Spatial overlap between Important Shark and Ray Areas (ISRAs) identified under Criterion B - Range Restricted with areas of high richness for range-restricted species in the Central and South American Pacific region.

(a) Gulf of California, (b) Pacific Central American Coastal, (c) southern part of Pacific Central American Coastal and northern part of Humboldt Current, and (d) Humboldt Current.

Fig 6. Spatial overlap between Important Shark and Ray Areas (ISRAs) identified under Sub-criterion D2 - Diversity with diversity hotspots in the Central and South American Pacific region.

(a) Gulf of California, (b) Pacific Central American Coastal, (c) southern part of Pacific Central American Coastal and northern part of Humboldt Current, and (d) Humboldt Current.

Fig 7. Reference analysis for contemporary (<20 years old) shark, ray, and chimaera research in the Central and South American Pacific region.

(a) Spatial trends (b) Topic research trends. QS: Qualifying Species, SS: Supporting Species, ABNJ: Areas Beyond National Jurisdiction.